A: Infrared Absorption á197Kñ.

B: It responds to the tests for Chloride á191ñ.

Diluent— Prepare a mixture of dimethyl sulfoxide and water (2:1).

Internal standard solution— Prepare a solution of absolute alcohol in Diluenthaving a known concentration of about 15µLper mL.

Standard stock solution— Transfer 50mLof the Diluentto a 100-mLvolumetric flask,add 0.64mLof isopropyl alcohol,dilute with Diluentto volume,and mix.

Standard solution— Pipet 1.0mLof the Standard stock solutioninto a 25-mLvolumetric flask,dilute with Diluentto volume,and mix (Solution 1).Transfer about 500mg of sodium chloride,accurately weighed,to a headspace vial,add 1.5mLof Solution 1and 1.5mLof the Internal standard solution,and mix.

Test solution— Transfer about 150mg of Mecamylamine Hydrochloride,accurately weighed,to a headspace vial,add about 500mg of sodium chloride,1.5mLof Diluent,and 1.5mLof the Internal standard solution,and mix.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 0.53-mm ×30-m capillary column whose internal wall is coated with a 1.0-µm film of liquid phase G16.This column is joined with a 0.53-mm ×25-m capillary column whose internal wall is coated with a 5.0-µm film of liquid phase G1.The G16column is connected to the detector,and the G1column is connected to the injector.The injection port temperature is maintained at about 100;the detector temperature is maintained at about 210;and the column temperature is maintained at 50for 10minutes,then increased at a rate of 5per minute to 110,then increased at a rate of 30per minute to 210,and maintained for 5minutes at 210.Nitrogen is used as the carrier gas,flowing at a rate of about 6.5mLper minute.The split flow is 15mLper minute.

Procedure— Allow the Standard solution,the Internal standard solution,and the Test solutionto stand for 20minutes at 90.Separately inject equal volumes (about 1mL)of the headspace of the Standard solution,the Internal standard solution,and the Test solutioninto the gas chromatograph,record the chromatograms,and measure the peak responses of the internal standard and isopropyl alcohol.Calculate the quantity,in ppm,of isopropyl alcohol in the portion of Mecamylamine Hydrochloride taken by the formula: in which WSis the amount,in ppm,of isopropyl alcohol in the Standard solution;WUis the weight,in mg,of Mecamylamine Hydrochloride taken to prepare the Test solution;and RUand RSare the peak response ratios of isopropyl alcohol to the internal standard obtained from the Test solutionand the Standard solution,respectively:not more than 2000ppm of isopropyl alcohol is found.

Internal standard solution— Proceed as directed in the Assay.

Solution 1— Prepare a solution of dl-camphene and USP Mecamylamine Related Compound A RSin the Internal standard solution containing 625µg of each per mL.

System suitability solution— Transfer about 125mg of USP Mecamylamine Hydrochloride RS,accurately weighed,to a 50-mLvolumetric flask,add 1mLof Solution 1,dilute with Internal standard solutionto volume,and mix.

Test solution— Use the Assay preparation.

Chromatographic system— Prepare as directed in the Assay.Chromatograph the System suitability solution,and record peak responses as directed for Procedure:the resolution,R,between the mecamylamine and mecamylamine related compound Ais not less than 5;the column efficiency is not less than 4000theoretical plates;the tailing factor is not more than 1.5;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject a volume (about 1µL)of the Test solutioninto the chromatograph,record the chromatogram,and measure all the peak responses.Calculate the percentage of each impurity in the portion of Mecamylamine Hydrochloride taken by the formula: in which riis the peak response for each impurity;and rsis the sum of the responses for all the peaks:not more than 0.5%of mecamylamine related compound Ais found;not more than 0.5%of dl-camphene is found;and not more than 1.0%of total impurities is found.

Internal standard solution— Transfer about 600mg of sodium hydroxide pellets to a 1Lvolumetric flask,dissolve in about 800mLof methanol.Add an accurately weighed quantity of about 1.7g of biphenyl to the flask,and dilute with methanol to volume.

Standard preparation— Dissolve an accurately weighed quantity of USP Mecamylamine Hydrochloride RSin Internal standard solution,and dilute with Internal standard solution,quantitatively and stepwise if necessary,to obtain a solution having a known concentration of about 2.5mg per mL.

Assay preparation— Transfer about 125mg of Mecamylamine Hydrochloride,accurately weighed,to a 50-mLvolumetric flask,dissolve in and dilute with Internal standard solutionto volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector connected to a 0.53-mm ×30-m capillary column,coated with a 1.5-µm film of liquid phase G27.The injection port temperature is maintained at about 200,the detector temperature is maintained at about 280,and the column temperature is at 120for 15minutes then increased at 25per minute to 250and maintained for 7minutes at 250.Nitrogen is used as the carrier gas at 7.4mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 4000theoretical plates;the tailing factor is not more than 1.5;and the relative standard deviation for replicate injections is not less than 2.0%.

Procedure— Inject equal volumes (about 1µL)of the Assay preparationand the Standard preparationinto the gas chromatograph,record the chromatogram,and measure the responses for the major peaks.Calculate the quantity,in mg,of C11H21N·HCl in the portion of Mecamylamine Hydrochloride taken by the formula: in which Cis the concentration of USP Mecamylamine Hydrochloride RS,in mg per mL,in the Standard preparation;and RUand RSare the peak response ratios of mecamylamine hydrochloride to the internal standard biphenyl obtained from the Assay preparationand the Standard preparation,respectively.